GB315391A - Improvements in luminous electric discharge tubes - Google Patents

Abstract

315,391. General Electric Co., Ltd., (Assignees of Patent-Treuhand-Ges. f³r Elektrische Gl³hlampen). July 14, 1928, [Convention date]. Vacuum tubes low-pressure metallicvapour apparatus. - The discharge in a gas or vapour lamp is guided through a hollow member of conducting refractory material preferably of metal such as tungsten which may be formed with interstices along its length so that the positive column is confined inside the member, possibly by a space charge outside. The hollow guide 16 may consist of a perforated sheet or of crossed wires or strip, and may be of oval, cylindrical, or prismatic shape. It is supported by nickel or molybdenum sleeves 15 on the necks of vessels 10 of quartz or ceramie material such as magnesium oxide which enclose the electrodes 7 and are connected together by rods or tubes 13, the structure being loosely mounted on foot tubes 3. The electrodes have enlarged heads carrying a material 9 which ensures the starting of a discharge and gives a good electronic emission. Sleeves 17 of quartz or ceramic material surround the electrodes so as to confine the discharge. The filling may consist of common gas such as nitrogen or carbon dioxide, rare gases such as neon, helium, or argon, or a mixture of rare and common gases. A metal such as mercury may be introduced or may form one or both of the electrodes. In modifications the hollow guide consists of (a) straight wires over which one or more wires are wound helically (b) straight wires mounted on an internal wire helix, (c) gauze covered with light-transmitting foil of refractory metal which may be chosen so as to modify the light emitted, or (d) a structure made of non-conducting rare earth oxides such as thorium, cerium, or scandium oxide, impregnated with molybdenum. Perforated plates may be built into the guide so as to increase the intensity of the light at certain points. Visible and infra-red radiation is obtained from a lamp with tungsten wire gauze, and ultra-violet light from the mercury filling. In the arrangement shown in Fig. 6, the electrode 8 is supported by an insulating disc 25 on a sleeve of magnesium oxide threaded over a pinch 4, and the lead 5 is surrounded by a tube 27 of insulating material. The electrode may evolve gas emitting light.